Perineural Pressures under the Pneumatic Tourniquet in the Upper Extremity

Abstract

The literature indicates that tourniquet-induced neurological injuries are relatively common and frequently occur at a subclinical level. In order to evaluate the pressure transmitted to the major peripheral nerves of the arm by an externally applied pneumatic tourniquet, a fully implantable biomedical pressure transducer was placed adjacent the radial, median and ulnar nerves in six cadaver upper extremities of average dimensions. This sensor allowed accurate, reproducible measurements of perineural pressures without requiring significant disruption of the normal anatomical structures of the test limb for its installation. At levels of tourniquet cuff inflation which are commonly used in clinical practice, there was little or no decrease in the pressure detected in the perineural regions over that applied to the surface of the limb. In addition, there was a steep gradient of perineural pressure between locations beneath the edge of the cuff and those under its midpoint. This was most marked at the highest levels of tourniquet inflation. At presently accepted levels of inflation, pneumatic tourniquet cuffs transmit high pressures to the peripheral nerves without any significant attenuation by the intervening soft tissues. The distribution of these forces is one which may subject the underlying nerves to deleterious shear forces, especially at higher levels of inflation.

Safety and efficacy of a new tourniquet system

“…The inflation pressure of a pneumatic cuff may not represent the actual pressure in the soft tissues under the cuff, and pressures vary widely from the applied pressures [6,12,13]. It is difficult to measure actual perineural pressures in the midst of surgery.…”

“…Most cases of neurologic complications are due to excessively high inflation pressure or long period of inflation [1-5]. Graham et al [6] used a fully implantable biomedical pressure transducer with cadaver upper extremities to demonstrate that tourniquet cuffs transmit high pressures to peripheral nerves under its midpoint without significant attenuation by the intervening soft tissues in an upper arm; he also reported a steep gradient of perineural pressure that decreased near the locations beneath the edge of the cuff. These results suggest the use of lower inflation pressure whenever possible.…”

Interface pressure, perceptual, and mean arterial pressure responses to different blood flow restriction systems

“…In a supine position, the cuff was placed on the proximal portion of the upper dominant leg. Limb circumference was measured at the midpoint of each cuff then divided by 4 to provide the positions for taping pressure sensors medially, anteriorly, laterally, and posteriorly, to examine all tissue areas compressed by the cuff at the midpoint where perineural pressures peak . Preliminary pilot work determined individual sensors provided a reliable and valid measure of interface pressure.…”

Tissue mechanics during temporal summation of sequentially cuff pressure‐induced pain in healthy volunteers and patients with painful osteoarthritis

“…the bones did not have any movement during the simulation, while the nodes of the soft tissue were left free (Manafi- Khanian et al, 2015a,b) to have displacement in space in all directions. A parabolic form of pressure along the axial direction of the limb (Graham et al, 1992;Manafi-Khanian et al, 2016) was defined in such a way that the average of the parabola was equivalent to the magnitude of the repeated pressure profile (Manafi-Khanian et al, 2016) previously extracted from the cuff system. The parabolic pressure distributions were applied circumferentially in the 6cm wide position of each chamber and on the surface of the model.…”